The specific aims of this study are to develop and evaluate a bacteriophage typing system for a newly recognized and important human enteric pathogen, Campylobacter jejuni. In this investigation, several methods of bacteriophage induction (exposure to mitomycin C and ultraviolet light) will be evaluated, the lytic spectra of bacteriophage infection on indicator lawns of C. jejuni isolates determined, and the "best" groups of these bacteriophages selected by a cluster analysis computer program for the proposed typing scheme. The sensitivity (percentage of typable cultures), specificity (percentage of cultures with a distinct bacteriophage lysis pattern), and reproducibility of the proposed typing scheme will be determined for representative human, animal, and environmental isolates of C. jejuni. This bacteriological and virological investigation will result in useful bacteriophage typing method that may be used in future studies of Campylobacter enteritis to provide a clearer understanding of the epidemiology of these infections. In the United States, C. jejuni is isolated as frequently as Salmonell and Shigella in patients with diarrhea. Better definition of the epidemiology of Campylobacter enteritis should resut in the identification of practical preventive measures that could be instituted to help control this public health problem.